Patent Document 1: JP-A-10-181403
Patent Document 2: JP-A-10-119619
Patent Document 3: JP-A-11-268566
Patent Document 4: JP-A-2003-81044
Patent Document 5: JP-A-2003-176844
Patent Document 6: JP-A-2005-225334
Patent Document 7: JP-A-2006-82772
Patent Document 8: JP-A-2006-88875
In vehicles, vehicle seats have been proposed in which a headrest is adapted to move forward to restrict the head of a seated person at the time of such as a collision.